The railway 5T system has existed for more than 40 years from the earliest THDS. The so-called 5T system mainly includes five independent system units, i.e., Train Coach Running Diagnosis System (TCDS), Trace Hotbox Detection System (THDS), Trackside Acoustic Detection System (TADS), Trouble of Moving Freight Car Detection System (TFDS) and Track Performance Detection System (TPDS), where, expect that TCDS is disposed in a running train, other four independent system units are separately disposed in four different detection stations on the trackside of railway steel rails and work independently. By a trackside single-function sensor, the detected vehicle-related safety information of trains running therethrough is transmitted, via wired cables, to hosts in different detection stations to be processed, and then the results of processing are transmitted to a superior vehicle safety monitoring center over a wired transmission network.
The wide application of the 5T system in the railway field plays a critical role in avoiding various accidents of running trains, for example, the occurrence of hotbox of vehicle axles, the falling-off of assemblies of running trains, etc., so that the probability of accidents of running trains is reduced greatly. With the continuous development of railway transportation, higher requirements on the stability and accuracy of the 5T system are proposed correspondingly. In other words, this requires the 5T system to successfully monitor trains within a certain region no matter in which state they are, and to acquire the safety state parameters of all running trains to be monitored integrally, accurately, reliably, comprehensively and thoroughly at one time.
These parameters include: running temperature distribution state of vehicle axles, whether or not sudden breakage occurs on the vehicle axle bearings, whether or not falling-off or deformation occurs on components related to the vehicle walking parts and vehicle chassis, whether or not there is any failure that the vehicle wheels are locked by the brake shoes, whether or not the heat distribution among the vehicle wheels is normal during the running, whether or not there is any unbalanced loading, etc. In this way, intuitive, scientific, and more reliable and accurate information can be provided for the train running safety command authority and the related command authorities to exactly master and dynamically track the vehicle safety state parameters of running trains.
However, there are many problems in the practical applications of the 5T system due to the restriction of its own technical conditions.
(1) As 5T consists of five different and independent system units, each of which detects different safety parameters, there is lack of comprehensive analysis and application of various parameters by multiple sensors, as a result, no complementary and comprehensive detection data can be provided for the system failure detection.
(2) With respect to the data information of 5T, the analog information collected by a trackside sensor is transmitted to a detection station, then the analog information is converted into corresponding digital information by the detection station through secondary processing, and the digital information is finally stored, judged and then processed.
(3) A Trace Hotbox Detection System (THDS) is provided in the 5T system. When an axle breaks down, it usually makes the axle temperature abnormal. Therefore, the failure of the axle may be found by detecting the axle temperature. To avoid missed detection, wrong detection and other errors, two different sensors are disposed in the trackside hot axle detection regions, respectively, in order to realize accurate detection. However, as both sensors are infrared thermistor temperature sensors which can detect the local temperature of the axles within a very small range (less than 40 mm2) only, but not the heat distribution of the vehicle axles as a whole, even not the temperature distribution outside of the train wheels, brake shoes and bogies. The failure of the wheels, brake shoes and bogies cannot be found in time and thus the requirement on comprehensive detection of train running safety parameters cannot be met.
(4) The trackside sensors of the 5T system are connected to the hosts in the detection stations via wired cables. However, as railways are ramified over the country and the environment of the railway trackside in some regions is very harsh, many connection cables have various failures correspondingly due to long-term work in the harsh environment, quite challenging the normal application of 5T and resulting in increased application and maintenance cost.
(5) As there is no industrial control computer for separately processing data information of the wheel sensors, the overall detection is abnormal when the speed of a running train is below 15 km/h, as a result, all results of detection are unreliable, unbelievable and unavailable. When the monitored train is in states in which a running train often encounters: for example, abruptly accelerates/decelerates, or, stops and then runs again, etc., the results of detection are invalid completely, just like the case mentioned above.
(6) There is no any monitoring camera device both indoor and outdoor the detection stations of the 5T system, so the outdoor working environment and indoor working situation cannot be known. When a trackside sensor breaks down, the system will be disabled due to the lack of further countermeasures.